The present invention relates to tools and methods for dispensing an ordered array of liquid drops onto a solid substrate, particularly for multiple testing in the biotecitnological field.
In the biotechnological field, it is often necessary to dispense liquid drops in an ordered array onto a solid substrate for performing multiple tests. There has been a strong desire to reduce the size of each individual liquid drop transferred on to the substrate so as to be able to increase the density of dots per unit area of substrate and at the same time minimize the volumes of expensive reagents required for the tests.
It is an aim of the present invention to provide a dropping tool for dispensing drops of liquid on to a solid substrate which is of relatively simple construction and with which it is possible to dispense drops of relatively small size with excellent reproducibility.
It is another aim of the present invention to provide an alternative and improved method for transferring a drop of liquid carried on a dropping tool on to a target substrate.
According to a first aspect of the present invention, there is provided a use of a dropping tool in a method of transferring drops of liquid on to a substrate, wherein a surface of the dropping tool for contact with the liquid has a first region which exhibits an affinity to the liquid to be transferred directly surrounded by a second region which exhibits a lower affinity to the liquid to be transferred than the first region: the topography of the first and second regions and the relative affinities of the first and second regions for the liquid to be transferred being selected such that when the dropping tool is dipped into and then removed from a source of the liquid to be transferred, the liquid adheres to the first region without substantially any adherence of the liquid to the second region.
According to a second aspect of the present invention, there is provided a dropping tool for transferring drops of a liquid onto a substrate wherein a surface of the dropping tool for contact with the liquid has a first region which exhibits an affinity to the liquid to be transferred directly surrounded by a second region which exhibits a lower affinity to the liquid to be transferred than the first region; the topography of the first and second regions and the relative affinities of the first and second regions for the liquid to be transferred being selected such that when the dropping tool is dipped into and then removed from a source of the liquid to be transferred, the liquid adheres to the first region without substantially any adherence of the liquid to the second region.
According to a third aspect of the present invention, there is provided a method for transferring drops of liquid carried on a dropping tool on to a substrate to form an ordered array of drops thereon wherein the drop of liquid is transferred without contacting the dropping tool with the substrate either directly or indirectly via the drop of liquid.
According to a fourth aspect of the present invention, there is provided a dropping tool for transferring drops of liquid on to a substrate, the dropping tool comprising a tip, at least one surface tapered towards the tip, and a capillary channel which leads from a position of the tapered surface remote from the tip to a reservoir located within the dropping tool.